1elpa_eigenvalues(3)        Library Functions Manual        elpa_eigenvalues(3)
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NAME

6       elpa_eigenvalues - computes the eigenvalues of a real symmetric or
7       complex hermitian matrix
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SYNOPSIS

11   FORTRAN INTERFACE
12       use elpa
13       class(elpa_t), pointer :: elpa
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15       call elpa%eigenvalues (a, ev, error)
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17       With the definitions of the input and output variables:
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19       class(elpa_t) :: elpa  ! returns an instance of the ELPA object
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21       datatype :: a
22              The matrix a for which the eigenvalues should be computed. The
23              dimensions of matrix a must be set BEFORE with the methods
24              elpa_set(3) and elpa_setup(3). The datatype of the matrix can be
25              one of "real(kind=c_double)", "real(kind=c_float)",
26              "complex(kind=c_double)", or "complex(kind=c_float)". The matrix
27              has to be symmetric or hermitian, this is not checked by the
28              routine.
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30       datatype :: ev
31              The vector ev where the eigenvalues will be stored in ascending
32              order. The datatype of the vector ev can be either
33              "real(kind=c_double)", or "real(kind=c_float)", depending of the
34              datatype of the matrix. Note that complex hermitian matrices
35              also have real valued eigenvalues.
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37       integer, optional :: error
38              The return error code of the function. Should be "ELPA_OK". The
39              error code can be querried with the function elpa_strerr(3)
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42   C INTERFACE
43       #include <elpa/elpa.h>
44       elpa_t handle;
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46       void elpa_eigenvalues(elpa_t handle, datatype *a, datatype *ev, int
47       *error);
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49       With the definitions of the input and output variables:
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52       elpa_t handle;
53              The handle to the ELPA object
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55       datatype *a;
56              The matrix a for which the eigenvalues should be computed. The
57              dimensions of the matrix must be set BEFORE with the methods
58              elpa_set(3) and elpa_setup(3). The datatype can be one of
59              "double", "float", "double complex", or "float complex". The
60              matrix has to be symmetric or hermitian, this is not checked by
61              the routine.
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63       datatype *ev;
64              The storage for the computed eigenvalues. Eigenvalues will be
65              stored in ascendig order. The datatype can be either "double" or
66              "float". Note that the eigenvalues of complex hermitian matrices
67              are also real.
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69       int *error;
70              The error code of the function. Should be "ELPA_OK". The error
71              codes can be querried with elpa_strerr(3)
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DESCRIPTION

75       Compute the eigenvalues of a real symmetric or complex hermitian
76       matrix.The functions elpa_init(3), elpa_allocate(3), elpa_set(3), and
77       elpa_setup(3) must be called BEFORE elpa_eigenvalues can be called.
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SEE ALSO

80       elpa2_print_kernels(1) elpa_init(3) elpa_allocate(3) elpa_set(3)
81       elpa_setup(3) elpa_strerr(3) elpa_skew_eigenvalues(3)
82       elpa_eigenvectors(3) elpa_skew_eigenvectors(3) elpa_cholesky(3)
83       elpa_invert_triangular(3) elpa_solve_tridiagonal(3) elpa_eigenvalues(3)
84       elpa_uninit(3) elpa_deallocate(3)
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88ELPA                            Sat Jul 15 2017            elpa_eigenvalues(3)
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